Question: Simplify the following expression: $z = \dfrac{1}{4n} - \dfrac{5}{6n}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4n$ and $6n$ $\lcm(4n, 6n) = 12n$ $ z = \dfrac{3}{3} \cdot \dfrac{1}{4n} - \dfrac{2}{2} \cdot \dfrac{5}{6n} $ $z = \dfrac{3}{12n} - \dfrac{10}{12n}$ $z = \dfrac{3 -10}{12n}$ $z = \dfrac{-7}{12n}$